Some new equipment for routine assessment of levels of soil infestation by the potato‐root eelworm, Heterodera rostochiensis Woll

Abstract

SUMMARYIn the examination of a soil sample for the cysts of potato‐root eelworm subjective errors are liable to occur at three particular stages of the technique, especially when large numbers of samples are being examined as a routine. Three pieces of equipment have been developed to mechanise these stages as far as practicable: (1) A centrifugal divider was adapted to obtain mechanically a uniform aliquot subsample from the full soil sample taken from the field; (2) A turntable was developed so that if cyst numbers are large the total may be estimated without picking off all the cysts present; (3) A magnetic stirrer was used to ensure that a reliable aliquot subsample is taken from the suspension of eggs for counting in the Fenwick slide. The inherent errors associated with each of these stages of the technique are examined.

The adenosine triphosphate content of cysts of Globodera pallida and G. rostochiensis as a possible quantitative estimate of field populations

“…Inaccuracy in the ATP assay may not be responsible, as a similar effect is shown in the viable egg count, but here it is less clearly defined partly because of the more variable data. The number of juveniles which hatch from cysts in laboratory experiments is not a constant proportion of their total content of eggs (Hesling, 1959). Possibly a greater percentage of the viable eggs failed to hatch in samples from Field A than from the cysts in the samples from Fields B, C and D. One factor that may be relevant is that the cysts from Field A were sampled a few months after cropping with potatoes, but the cysts in the remaining fields were formed prior to the summer before their collection.…”

“…A sample pooled from forty to fifty soil cores was taken from each of twenty plots of 20 x 6 yd (18.3 x 5-5 m), arranged in a random block design. The remainder of each sample was used for this study, in an air-dried state, after its viable egg count per g soil had been determined by standard procedures (Fidler, 1963) at the ADAS regional laboratory in Leeds.…”

A column elutriator for extracting cyst nematodes and other small invertebrates from soil samples

“…In later tests the whole of the filter paper was searched after the debris was collected on the paper using a Buchner Funnel (Fidler, 1963). In later tests the whole of the filter paper was searched after the debris was collected on the paper using a Buchner Funnel (Fidler, 1963).…”

“…In this test the 'float' was transferred from the 250 pm sieve to an 18.5 cm diameter Whatman filter paper on the top of a specially constructed Buchner funnel, the water removed with a filter pump and the filter paper placed for counting on a turntable of the design of Fidler (1963). The Wye Washer process was as described above with a flow-rate of 10 litres/min for about 10 min per sample.…”

The ATP method for rapid assessment of the efficacy of a single application of a fumigant against Globodera spp. in field soils

“…Advisory soil samples from 26 sites were obtained by the regional centres of the Agricultural Development and Advisory Service (AD AS) at Leeds and Shardlow. The samples were coded and duplicate batches of cysts were extracted from either 50 g or approximately 100 g subsamples off air-dried soil using standard procedures (Fidler, 1963: Shepherd. 1970).…”